Intracranial Administration of P Gene siRNA Protects Mice from Lethal Chandipura Virus Encephalitis

Kumar, Satyendra; Arankalle, Vidya A.

Initially, a total of 12 siRNAs (4 for P gene and 8 for M gene) were screened in-vitro. Co-transfection of pAcGFP1N1-CHPV-P plasmid and all the P gene siRNAs identified P-2 siRNA as the most potent in perturbing P gene expression (Fig 2) . M gene siRNAs were directly validated with the virus. P-2, M-5 and M-6 siRNAs were equally efficient in inhibiting CHPV induced cytopathic effects (Fig 3) . Replication inhibition in siRNA treated cells was also confirmed by 2logs reduction in the virus titer as evidenced by both plaque assay and real time one step RT-PCR (Fig 3b) . Unfortunately, use of combinations of effective siRNAs at different concentrations did not yield additive benefit. A possible explanation could be that cells have a limited capacity to assemble the RNA-induced silencing complex (RISC) and siRNA's compete for the available RISC pool present in the cells [30] . Similar observations have been reported for two respiratory viruses, respiratory syncytial virus and parainfluenza virus [15, 31] .